The invention relates to an anti-fungal composition comprising zinc or copper salts of organic acids.
Zinc and copper salts of high molecular weight organic acids have long been used to prevent biological degradation of wood and of other organic materials. Organic acids used to prepare such salts include: those mixtures of acids known as naphthenic acids; tall oil acids; stearic acid; oleic acid; acids derived from linseed oil; and, more recently, mixtures of primary and secondary or tertiary branched-chain carboxylic acids synthesized by various routes from petroleum. For application as a wood preservative, the copper or zinc salt of such an acid is most commonly dissolved in a petroleum solvent (such as paraffin or white spirit) or a coal tar solvent, although it may be dissolved in water by, for example, the technique disclosed in co-pending U.S. patent application No. 904,606, filed May 10, 1978 by Edward Austin Hilditch now U.S. Pat. No. 4,193,993, issued on Mar. 18, 1980 and reissued as U.S. Pat. No. Re. 31,576 on May 1, 1984 (based on reissue application Ser. No. 357,225, filed Mar. 11, 1982). For application to organic materials other than wood (for example, hessian, cotton and other textiles, rope and cordage) these salts may be dissolved in the same way as when applied to wood or they may be formed into an emulsion.
However, whatever means is adopted to apply the salts to the material to be treated, once the salts have been applied, it is essential that they should not easily be removed in the course of normal use of the material to which they have been applied.
We have now surprisingly found that the use of a mixture of zinc or copper salts of primary and/or secondary saturated acyclic carboxylic acids with zinc or copper salts of tertiary saturated acyclic carboxylic acids provides a preservative of greater effectiveness than if either type of acid were used alone.